Pressure-sensitive adhesive tapes and specifically printable, fire-retardant, pressure-sensitive adhesive tapes have many applications, for example, for use in aircraft, ships, computers, electrical appliances, and in audio and visual equipment as wrapping for electronic components where a flame retardant thermal insulator is required and the ability to print an identification code is necessary, i.e., for transistors, capacitors, resistors and electrical wires as identification labels and/or as insulation; and for identification or labelling purposes for hydraulic lines, etc.
Pressure-sensitive adhesive tapes can be applied with hand pressure in the absence of solvents or heat and stick aggressively to most common surfaces. Cloth, paper, films, foils, strand reinforced backings as well as many laminates have been employed as tape backing for pressure sensitive adhesive tapes. These are always thin and flexible to conform readily to the surface upon which they are applied. The most commonly used films for pressure-sensitive adhesive tapes are cellophane, polyvinyl chloride, polyester, polyethylene, polypropylene and the cellulose acetate films. The films are generally coated with a very thin anchor coating called a primer to improve the bonding of the adhesive to backing. The films are often coated on the opposite side with a release agent to reduce the adhesion of the adhesive to the backside of the next layer of tape when in roll form. Stearate chromic chloride, octadecyl acrylate-acrylic acid copolymers, and similar polymers, as well as cured dimethyl silicone coatings, are used as release agents.
The prior art provides many examples of pressure-sensitive adhesive tapes both printable and unprintable as well as fire-retardant and non-fire retardant.
For example, U.S. Pat. No. 3,543,920 discloses a pressure-sensitive adhesive tape which is coated with a release composition which incorporates a printable film forming resin and a copolymer of stearyl methacrylate and acrylonitrile as a release agent to provide easy release from the roll on which it is wound and good printability.
U.S. Pat. No. 3,967,031 describes a pressure-sensitive adhesive tape having a backsize or release coating which is a blend of 5-80 parts cellulose acetate butyrate and 95-20 parts copolyester and/or acrylate copolymer and having both printability and low-unwind characteristics.
U.S. Pat. No. 3,978,274 describes a pressure-sensitive tape with a printable release coat on the side opposite to the adhesive face, which release coat comprises a ternary system consisting of vinyl film former, an acrylic resin and a polyamide plasticizing resin.
U.S. Pat. No. 4,056,661 provides a printable self-wound tape by coating a discontinuous layer of silicone resin as a release agent over a coarse, and therefore printable, surface layer of pigment and binder.
Blum et al., in U.S. Pat. No. 4,070,523 use polyketone resins blended with a monomeric or polymeric release agent such as long chain urethanes of polyvinyl alcohols as an ingredient of the release coating for a flexible pressure-sensitive tape.
U.S. Pat. No. 4,587,156 discloses a printable, self-wound, pressure-sensitive adhesive tape in which the backsize coating is comprised of a ternary mixture of an octadecylacrylate release agent, a primer resin of chlorinated polyolefins and an ink anchoring resin made of cellulose acetate butyrate.
U.S. Pat. No. 4,587,167 discloses a release-coating composition for producing a pressure-sensitive, printable adhesive tape consisting of a ketone resin, a polyamide resin and a ketone resin modified by reaction with alkylisocyanates. In addition, the printing ink is specific to this system and is modified with polyamide resins and silicone polymer as a step agent.
U.S. Pat. No. 4,599,260 issued to Truskolaski et al. describes a directly printable tape with a release coating which consists of polyvinyl carbamate polymer, a common release agent. To render this material printable the release coating must be heated on the coated substrate and printed with an ink that has been modified with resinous binder and chlorinated polyolefins.
U.S. Pat. No. 4,992,331 describes a flame retardant conformable adhesive tape which consists of a water-impermeable chlorinated polyethylene backing layer, an evenly tearable synthetic fiber cloth or scrim, a flame-retardant adhesive which is preferably rubber-based and a thin two coat layer between the backing and the scrim.
Similarly, pressure-sensitive flame retardant laminate material has been disclosed in U.S. Pat. No. 4,693,920. This pressure-sensitive composite material is not a self-wound product and incorporates in release liners into its composition.
It is an object of the present invention to provide a novel self-wound, fire-retardant, pressure-sensitive adhesive ("PSA") tape. In addition, it is an object of the present invention to provide such a PSA tape which can be used in electrical applications.
It is an object of the present invention to provide a printable PSA adhesive tape which does not necessitate the use of a separate release agent or release coating.
It is a further object of the present invention to provide a simple three part system for a printable fire-retardant PSA adhesive tape which has good adhesive, release and self-winding properties.
Another object of the present invention is to provide a PSA adhesive tape which comprises a flame retardant adhesive on a polyester film substrate.
It is yet another object of the present invention to provide a rubber base prime coat that has excellent release properties while accepting flexographic printing ink.